QCAD.org Forum

Hi Qcad Friends,

I noticed a slow operation using my Qcad Pro in my notebook.
In the pictures attached, you can see the htop output.

In the first picture, the qcad is running with the file opened and in the second one zooming.

The system output from Qcad About output is below:

Versions
QCAD version: 3.27.5.0
Date: May 6 2022
Qt version: 5.8.0
Compiler version: gcc 4.8.1
Build date: May 6 2022
Revision: 28de0449313fa955a114b959b8aba6af11c1a59d

5.10.0-16-amd64 #1 SMP Debian 5.10.127-1 (2022-06-30) x86_64 GNU/Linux

Any guess how to have a better experience?

Best regards!

Hello,

rodmaru wrote: ↑

Fri Sep 02, 2022 1:41 am

In the pictures attached, you can see the htop output.

you forgot to attache the pictures.
BTW: An attached drawing file like dxf/dwg would help us even more to investigate the reason of the slow down issue.

Hi Husky,
thank you for your reply.
I attached the files but something wrong happened.
Here we go again.
Ok the dxf file is attached too.

Hi rodmaru - thanks for the files.

rodmaru wrote: ↑

Fri Sep 02, 2022 1:41 am

Any guess how to have a better experience?

sorry, I don't have Linux but on my standard Win10/64 system/16 GB RAM the slow down effect is reproducible too. This said it is not dramatically. I tried hard to blow the roof off of my CPU with zoom in/out but I was only able to achieve a 30% CPU load. I would considered that an acceptable value.


However. This drawing has a non QCAD CAD history what is noticeable e.g at block names with invalid names like *X82. Those names are not allowed in QCAD. It is debatable if that is a possible future problem or not but to be on the safe side I recommend to fix that below Menu/Misc/Blocks/Fix Block Names.
In addition to that the drawing contains a lot of hatches (>175). Rendering of hatches is a performance compromising process. I recommend to move all hatches to a dedicated hatch layer and turn that layer then invisible as long you don't need the hatch information visible in your drawing. The same procedure is recommended with the 1300+ Text entities. Most likely it will speed up the performance.

Lets talk about blocks. Massive blocks will slow down a drawing! I noticed that e.g. block p1 and p2 are used for a similar drawing situation. It is not common or recommenced to built a massive block like those for such a task. A block is meant as a recurring source for identical designs like a flange, bolts and nuts or pumps, brackets etc. etc.. Instead building a massive block just use move/copy or a similar tool to get a duplicate of p1 or p2 in Model_Space.
To test this affect on blocks just explode them all and see how it affects the speed of zooming in/out. If you like/need to stick to those massive blocks just close the drawing after the test without saving it and the last saved structure is preserved.

BTW: I noticed 89 blocks in the Block List but only 43 are used in the drawing. If possible purge them to reduce the overall size of the drawing. My best guess is the drawing will shrink by approx. 40%. Menu/Blocks/Purge Unused Blocks.

Regardless keeping those massive blocks or not the best way to maintain a satisfying drawing handling would be to change your navigation method. You can eliminate most of the zoom in/out action with using the "View List" (Menu/View/View List) instead. Nothing is faster then that method and you are still able to zoom further in to catch every detail.
It takes only a few minutes to set it up (use meaningful names for each view) and you will benefit immediately of it.

Just my 2 cents.

rodmaru,

With your file I experience a zoom in/out lag with the mouse wheel of about 3fps starting from auto zoomed. (32bit Win7 old HDD)
This is not uncommon and it gets better the further we zoom in.
I can't find anything that is known to slow down QCAD in a major way.
Still, I also did experience a complete halt from time to time.

A 3.6Mb dxf is not a small project anymore, QCAD need to re-render about 12000 entities each zoom state.
Among them 1200 polylines, 1435 text based and 64 splines.

Some tips & remarks:
The Block in Block in Block ... construction can be an issue.
- I would Explode (XP) the first level of Blocks except 'folhaA0'.
- There are some odd block constructions that can be simplified ... streamlined further.

Hatches in a Block can be an issue especially when patterned, what is not the case.
- I would represent thick lines (e.g. copper bars) with a polyline and a Global Width instead of a solid hatch including its boundary.
- One can do the same for filled arrows.

I could purge 46 unused Blocks and 5 Layers.

I see Text disappear and reappear depending the zoom state.
- There are 58 different fonts, most of them are called 'textstyle' and a number.
- All but a few are not on my system and it seems that some are rendered as 'Arial' or 'Standard' over here.
- Still, not all glyphs are rendered, it is in Portuguese I suppose.
- Block 7 ... 4 Text items are exploded to 40 polylines.
- I would Substitute Fonts (FF) with installed types and use QCAD line art CXF fonts instead of TTF where required/possible.

Some kind of splines may cause an issue and then especially when patterned.
- I would not use a spline for each 'Indicacao da bitola do eletroduto'.
- One could Explode (XP) the other splines to polylines.


Does changing all this speed up the rendering? No, not significantly.
One can still avoid some zooming lags with stored views.

Reading Husky's reply just now, I think we are on the same level of advice.

Regards,
CVH

Husky wrote: ↑

Sat Sep 03, 2022 6:29 am

Lets talk about blocks. Massive blocks will slow down a drawing!
...
A block is meant as a recurring source for identical designs like ...

I do agree but also see a duality.

More than once Andrew did state that layers are meant for grouping things that should be displayed alike.
And Blocks typically group entities which are all part of the same object in the real world (e.g. a bolt, a plant, a machine part, etc.).

But Blocks are also used to group entities, parts and sub-parts together that belong logically together.
It is then not uncommon to group things in a Block like a first and second floor.
With a lot of details you automatically get what you call 'Massive blocks'.

When we look deeper into this, we find that ACAD supports Groups besides Blocks.
Groups have a little similarity with Blocks and they can also be used in places where you want to make an object from multiple geometries.

e.g. a Group called 'dining table' made up of a 'table' Block and 4 'chair' Blocks.
That can be grouped again as an arrangement of dining tables.
Under QCAD Groups are simply Blocks again.

Regards,
CVH

Thanks, Husky and CVH,

Very interesting points.
Doing by parts. I explode the first blocks and deleted the hatches and the speed was increased.
I noticed that the filter cannot search for hatches inside blocks from outside.
Now I will go to fix the odd blocks to clean up the draw.
Husky said about the size limit for a DXF is considered a small draw. Any difference between using DXF or DWG?

Best regards,
Rodrigo

rodmaru wrote: ↑

Sat Sep 03, 2022 3:28 pm

I noticed that the filter cannot search for hatches inside blocks from outside.

Indeed, you are searching in the Model_Space Block untill you edit another Block.

rodmaru wrote: ↑

Sat Sep 03, 2022 3:28 pm

Any difference between using DXF or DWG?

Not that I can think of except disk storage space.
A DWG is a binary file, A DXF is textual, both are read and entities are handled as objects.
Any DWG file will be stored in DXF format as backup in auto save mode.

Regards,
CVH

Thank you, Husky and CVH, for looking into this issue!

I have cleaned up the drawing a little bit.
Nothing was better than exploding the massive blocks. Actually, inside those massive blocks, was very easy to zoom in and out.
My next test will run the same zoom issue in a compiled QCAD version, on the same machine. I had compiled the QCAD in this machine but I deleted it after buying the PRO version. Just to play with my CPU and his cores.
I will be back soon with some Stats from this little Thinkpad X220 Corei5/8GB.

Kind regards,

Rodrigo